V$SYSTEM_EVENT

V$SYSTEM_EVENT displays information on total waits for an event. Note that the TIME_WAITED and AVERAGE_WAIT columns will contain a value of zero on those platforms that do not support a fast timing mechanism. If you are running on one of these platforms and you want this column to reflect true wait times, then you must set TIMED_STATISTICS to TRUE in the parameter file; doing this will have a small negative effect on system performance.